how many form fields is the ideal for cta landing page forms

 Best practices for creating CTA forms: Using forms  for creating a call to action page in your landing page :Forms are your best methods of collecting user information and customer data points. The amount of data ad information you ask for ( the number of form fields you have in the form should tally directly with the degree of upfront prospects screening you wish to filter your qualified leads or information you need to qualify a lead as moderate, hot and warm)
Most often visitors perceive value of benefit in exchange for their personal data.For example users  give their details based on the demand of your proposition. How important is the value of your product or service offering:When a visitor perceives something as more valuable they are willing to release more information. Conversely the lower the perceived value.. the lower will be the filters which user will be willing to part with their personal information.

A customer may be willing to part with their credit card for a one month trial or a subscription offfer, but they would not be willing to part with the same credit card number for a ebook.your basic point of action should be to elevate the power of offering or promising something which they have not been exposed or seen earlier . Sure that depends upon your product if you wish to hand them freebies or wish to capture only the email id and phone number

Ultimately its a wise strategy to keep your form filter set at capturing information like email id/mobile number. as form fatigue tends to grip the online user and they will over a time will part with only a few information before they move elsewhere. I usually recommend a form having no more than 3 form fields  First and last name Email ID Phone number If you have more than these 3 fields, pls designate the forms with mandatory for those fields which are must for filling the form and those which are non mandatory. For Business to Business companies you might want to inlclude :business email :Title and Number of employees